Assembly including two pipe lengths assembled with an interface joint

ABSTRACT

The invention relates to an assembly including a first pipe length ( 1 ) and a second accommodating mechanical pipe length ( 2 ), said first length ( 1 ) being assembled in said second length ( 2 ) by means of an interface joint ( 4 ), conductor of electric current. As it is assumed that said first length ( 1 ) and said second length ( 2 ) are also conductors of electric current, the joint ( 4 ) thus provides good sealing between the first pipe length ( 1 ) and the second pipe length ( 2 ) in order to prevent leakages of fluid and to prevent the formation of inopportune electric arcs due, for example, to static electricity.

FIELD OF THE INVENTION

The invention relates to an assembly consisting of two pipe lengthsassembled with an interface joint.

PRIOR ART

Inside certain voluminous structures, such as aircraft for example,several zones exist in which different fluids transit through differentconduits. Some of these zones are particularly sensitive on account ofthe nature of the fluid passing through them, and must therefore be theobject of special attention as regards safety.

The zone of an aircraft that includes the fuel tank and the associatedconduits must therefore imperatively be designed so as to preventleakages of fuel or other fluids, as well as the production ofinopportune electric arcs.

SUMMARY OF THE INVENTION

The assemblies according to the invention allow these two problems to beresolved in a certain and stable manner, while being designed to preventthem from degrading over time.

The object of the invention is an assembly including a first pipe lengthand a second pipe length, said first length being assembled in saidsecond length by means of at least one interface joint capable of cominginto contact with said lengths.

According to the invention, the joint, the first pipe length and thesecond pipe length are conductors of current, said joint beingovermoulded in one of said lengths so as to be in electrical contactwith said length.

In this way, the joint has a dual function:

-   -   of ensuring sealing between the two pipe lengths so as to        prevent leakages of a fluid that could be present in at least        one of the two lengths, and    -   of discharging electrical current due, for example, to static        electricity, and potentially capable of being created between        the two pipe lengths.

Furthermore, by being overmoulded in one of the two pipe lengths, thejoint thus possesses positional stability, preventing it from movingand/or becoming deformed during assembly or over time to the extent ofbeing unable to provide its sealing function.

According to a possible characteristic, the first length is capable ofpenetrating into the second length so that said lengths present anoverlap zone, said joint being placed in said zone, while being incontact with the length in which it is not overmoulded.

According to a possible characteristic, the joint extends at leastpartially along the circumference of the overlap zone.

According to a possible characteristic, the joint is plastic, loadedwith carbon black.

According to a possible characteristic, the joint is overmoulded in arecess of the outer surface of the first pipe length.

According to a possible characteristic, the joint is overmoulded in anannular recess of the inner surface of the second pipe length.

According to a possible characteristic, the recess has a bottom hollowedout by a central groove extending the entire length of said recess.

According to a possible characteristic, the overmoulded joint emergesfrom the recess in such a way as to define a salient flange.

According to a possible characteristic, the joint is hot overmoulded inthe first or second pipe length, so that said joint is in directelectrical contact with the length in which it is overmoulded.

According to a possible characteristic, the joint is overmoulded in thefirst or second pipe length by means of a conductive adhesive, so thatsaid joint is in electrical contact with the length in which it isovermoulded.

According to a possible characteristic, the first length is a tube forsupplying a liquid fluid, the second length being a hollow mechanicalconnector, and said tube being pushed into said connector.

According to a possible characteristic, the tube is a single piece andis made of a material to be chosen among a plastic with carbon black,glass fibre with carbon black, a mixture of glass fibre and plastic withcarbon black, and a metal.

According to a possible characteristic, the connector is made of amaterial to be chosen among a plastic with carbon black, glass fibrewith carbon black, a mixture of glass fibre and plastic with carbonblack, and a metal.

The invention has, as another object, an aircraft including an assemblyaccording to the invention.

The invention has, as another object, a method of assembling a firstpipe length into a second pipe length by means of at least one interfacejoint. According to the invention, said first pipe length, said secondpipe length and said joint are conductors of current, and said at leastone joint is overmoulded in at least one of said lengths so as to be inelectrical contact with said at least one length, said method includinga step for inserting the first length of pipe into the second length ofpipe so as to position said at least one joint in electrical contactwith the other length.

According to a possible characteristic, an overlap zone is createdbetween the first and the second pipe lengths during said insertionstep, the joint being placed in said zone, while being in contact withthe length in which it is not overmoulded.

The invention has, as another object, a pipe length. According to theinvention, said length is an electrical conductor and has at least oneinterface joint that is an electrical conductor, said joint beingovermoulded in said length so as to be in electrical contact with thelatter.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description is given below of two possible embodiments of anassembly device according to the invention, making reference to FIGS. 1to 5.

FIG. 1 is a perspective view of an assembly according to the invention,

FIG. 2 is a longitudinal section of an assembly according to a possibleembodiment of the invention,

FIG. 3 is a longitudinal section of an overmoulded joint in a tube ofthe assembly illustrated in FIG. 2,

FIG. 4 is a partial perspective view of the tube of the assemblyillustrated in FIG. 2,

FIG. 5 is a longitudinal section of a tube assembled in a connectoraccording to another possible embodiment of an assembly according to theinvention.

DETAILED DESCRIPTION

In order to remove any ambiguity, it must be specified that theconnector is not an electrical connector in the conventional meaning ofthe word, but a mechanical receptacle capable of accommodating theextremity of a tube.

With reference to FIG. 1, a possible embodiment of an assembly accordingto the invention includes a first pipe length in the shape of a fuelsupply tube 1, and a second pipe length in the shape of a mechanicalconnector 2, implanted in the structure 3 of an aircraft. This tube 1can be likened to a hollow single-piece cylinder and is made of aresistive material, such as, for example, a metal or a mixture ofthermoplastic polymer and glass fibres loaded with carbon black. Theconnector 2 is cylindrical and is preferably made of metal or in aplastic loaded with carbon black. It must be specified that said tube 1and said connector 2 are conductors of electrical current. The insidediameter of the connector 2 is greater than the outside diameter of thetube 1, so that said tube 1 can be assembled in said connector 2 bypushing it in. The connector 2 has an extremity 12, which is attached tothe structure, and an opposite free extremity 14, capable ofaccommodating the fuel supply tube 1.

With reference to FIGS. 2, 3 and 4, a possible embodiment of an assemblyaccording to the invention includes a joint 4 overmoulded in the fuelsupply tube 1 at one 5 of its extremity zones. More precisely, in saidextremity zone 5, the tube 1 presents an annular recess delimited by twoannular shoulders 6,7, projecting from the outer surface 8 of said tube1. One 6 of said shoulders comes flush with the extremity of the tube 1.The recess extends 360° around the tube 1 and has a cylindrical bottomhollowed out in the wall of the tube 1 by a central annular groove 9,extending the entire length of said recess. The joint 4 is a conductorof electric current and can, for example, be made of a plastic loadedwith carbon black. Once the joint 4 has been overmoulded in the recessof the tube 1, it projects from the two shoulders 6, 7 delimiting saidrecess, while completely occupying the volume of the central groove 9 aswell as the volume between said shoulders 6,7. It thus creates a flange,locally and radially widening the zone of the extremity 5 of said tube1. The central groove 9 is designed to enlarge the contact surfacebetween the joint 4 and the tube 1. In this way, the joint 4 is solidlysecured to the tube 1, and the electric current can easily transitbetween said tube 1 and said joint 4. However, even though the presenceof this groove 9 improves the embodiment conditions of an assemblyaccording to the invention, it is not indispensable to such anembodiment.

The joint 4 is deposited in the recess in the tube 1 so that it comesinto electrical contact with said tube 1. In order to achieve thisresult, said joint 4 can:

-   -   either be directly hot overmoulded in the recess of the tube 1.        In fact, in this case, the contact between said joint 4 and said        tube 1 is sufficiently great to ensure satisfactory electrical        contact between these two parts 1, 4,    -   or be overmoulded at a lower temperature in said recess after a        thin coat 10 of conductive adhesive has been deposited in said        recess. In fact, this conductive adhesive 10 will contribute to        improving the contact conditions between the joint 4 and the        tube 1 and thus allow an electrical contact to be achieved        between these two parts 1, 4.

With reference to FIG. 2, once the joint 4 has been satisfactorilyovermoulded in the recess of the tube 1, the tube 1 is routed towardsthe fixed connector 2 so as to present the extremity zone 5incorporating the joint 4 before said connector 2. The tube 1 is thenpushed inside the fixed connector 2 via this extremity zone 5, in thedirection indicated by the arrow 13 illustrated in FIG. 2. Theassembling of the tube 1 in the connector 2 creates an overlap zonebetween these two lengths, leaving a free space 15 between the outersurface 8 of said tube 1 and the inner surface 16 of said connector 2.During the push-in phase of the tube 1 in the connector 2, the joint 4finds itself in this overlap zone and makes close contact with the innersurface 16 of said connector 2. By means of these different assemblyphases, a possible embodiment of an assembly according to the inventionis obtained, said assembly constituting a tube 1 and a mechanicalconnector 2, said tube 1 being partially inserted in said connector 2 bymeans of an interface joint 4 overmoulded in said tube 1.

With reference to FIG. 5, according to another possible embodiment of anassembly according to the invention, the joint 104 is overmoulded in arecess of the connector 102, in the same conditions as those describedpreviously, when said joint 4 is overmoulded in a recess of the tube 1.For this embodiment, the recess is annular and is delimited by twoannular shoulders 106, 107 projecting from the inner surface of theconnector 102. One 106 of said shoulders comes flush with the freeextremity of the connector 102. The recess extends 360° around theconnector 102 and has a cylindrical bottom hollowed out in the wall ofthe connector 102 by a central annular groove 109, extending the entirelength of said recess. Once the joint 104 has been overmoulded in therecess of the connector 102, it projects from the two shoulders 106, 107delimiting said recess, while completely occupying the volume of thecentral groove 109 as well as the volume between said shoulders 106,107. It thus creates a flange, locally and radially reducing the sectionof the connector 102.

The materials that constitute the joint 104, the connector 102 and thetube 101 are identical to those described for the preceding embodiment.The techniques for overmoulding the joint 104 in the recess of theconnector 102 are also similar to those described for the precedingembodiment.

Once the joint 104 has been satisfactorily overmoulded in the recess ofthe connector 102, the tube 101 is pushed inside the fixed connector 102in the direction indicated by the arrow 113. The assembling of the tube101 in the connector 102 creates an overlap zone between these twolengths, leaving a free space 115 between the outer surface 108 of saidtube 101 and the inner surface 116 of said connector 102. During thepush-in phase of the tube 101 in the connector 102, the joint 104 findsitself in this overlap zone and makes close contact with the outersurface 108 of said tube 101.

Once the tube 1, 101 has been assembled in the connector 2, 102, thejoint 4, 104 provides, on one hand, good sealing between these twolengths 1, 101 and 2, 102, while preventing fuel leaks, and on theother, close electrical contact with said lengths 1, 101 and 2, 102 soas to discharge parasite electric currents and to prevent the creationof electric arcs. In fact, it is assumed that the connector 2, 102 isconnected to earth via the structure 3 to which it is secured, thusallowing parasite electric currents to be discharged.

An assembly according to the invention offers several advantages:

-   -   it provides enhanced safety within the installation in which it        is installed by preventing fuel leaks and the creation of        electric arcs due, for example, to static electricity,    -   it improves the reliability of the installation,    -   it creates reductions of mass,    -   it enables the implementation of a fuel supply tube having a        specific resistance, variable according to the proportion of        carbon injected into said tube.

1. Assembly including a first pipe length (1, 101) and a second pipelength (2, 102), said first length (1, 101) being assembled in saidsecond length (2, 102) by means of at least one interface joint (4, 104)capable of coming into contact with said lengths (1, 2, 101, 102),wherein the joint (4, 104), the first (1, 101) pipe length and thesecond (2, 102) pipe length are conductors of current, and that saidjoint (4, 104) is overmoulded in one of said lengths (1, 102) so as tobe in electrical contact with said length (1, 102).
 2. Assemblyaccording to claim 1, wherein the first length (1, 101) is capable ofpenetrating into the second length (2, 102) so that said lengths (1, 2,101, 102) present an overlap zone, and in that said joint (4, 104) isplaced in said zone, while being in contact with the length (1, 2, 101,102) in which it is not overmoulded.
 3. Assembly according to claim 2,wherein the joint (4, 104) extends at least partially along thecircumference of the overlap zone.
 4. Assembly according to claim 1,wherein the joint (4, 104) is plastic, loaded with carbon black. 5.Assembly according to claim 1, wherein the joint (4) is overmoulded in arecess of the outer surface (8) of the first pipe length (1). 6.Assembly according to claim 1, wherein the joint (104) is overmoulded inan annular recess of the inner surface (116) of the second pipe length(102).
 7. Assembly according to claim 5, wherein the recess has a bottomhollowed out by a central groove (9, 109) extending the entire length ofsaid recess.
 8. Assembly according to claim 5, wherein the overmouldedjoint (4, 104) emerges from the recess in such a way as to define asalient flange.
 9. Assembly according to claim 1, wherein the joint (4,104) is hot overmoulded in the first (1) or second (102) pipe length, sothat said joint (4, 104) is in direct electrical contact with the length(1, 102) in which it is overmoulded.
 10. Assembly according to claim 1,wherein the joint (4, 104) is overmoulded in the first (1) or second(102) pipe length by means of a conductive adhesive, so that said joint(4, 104) is in electrical contact with the length (1, 102) in which itis overmoulded.
 11. Assembly according to claim 1, wherein the firstlength is a tube (1, 101) for supplying a liquid fluid, and in that thesecond length is a hollow mechanical connector (2, 102), said tube (1,101) being pushed into said connector (2, 102).
 12. Assembly accordingto claim 11, wherein the tube (1, 101) is a single piece and is made ofa material to be chosen among a plastic with carbon black, glass fibrewith carbon black, a mixture of glass fibre and plastic with carbonblack, and a metal.
 13. Assembly according to either claim 11, whereinthe connector (2, 102) is made of a material to be chosen among aplastic with carbon black, glass fibre with carbon black, a mixture ofglass fibre and plastic with carbon black, and a metal.
 14. Aircraftincluding at least one assembly according to claim
 1. 15. Method ofassembling a first pipe length (1, 101) into a second pipe length (2,102) by means of at least one interface joint (4, 104) wherein the firstpipe length (1, 101), the second pipe length (2, 102) and the joint (4,104) are conductors of current, and in that said at least one joint (4,104) is overmoulded in at least one of said lengths (1, 2, 101, 102) soas to be in electrical contact with said at least one length (1, 2, 101,102), said method including a step for inserting the first length (1,101) of pipe into the second length (2, 102) of pipe so as to positionsaid at least one joint (4, 104) in electrical contact with the otherlength (1, 2, 101, 102).
 16. Method according to claim 15, wherein anoverlap zone is created between the first (1, 101) and the second (2,102) pipe lengths during said insertion step, the joint (4, 104) beingplaced in said zone, while being in contact with the length (1, 2, 101,102) in which it is not overmoulded.
 17. Length (1, 2, 101, 102) ofpipe, wherein is an electrical conductor and has at least one interfacejoint (4, 104) that is an electrical conductor, said joint (4, 104)being overmoulded in said length (1, 2, 101, 102) so as to be inelectrical contact with the latter (1, 2, 101, 102).